Integrated circuits use shallow trench isolations to separate and electrically isolate different active areas. The shallow trench isolation is typically an insulator embedded in a substrate of the integrated circuit, so the material of the substrate is interrupted at the shallow trench isolation. Integrated circuits also use many transistors, resistors, and other electrical components positioned on the substrate, and some of the electrical components use silicon germanium embedded within the substrate. In particular, some “P” type transistors use embedded silicon germanium for the source and drain, because the silicon germanium can be produced with a strained crystal structure that improves electron mobility. The silicon germanium is epitaxially grown from the crystalline structure of the substrate, and does not grow on areas without a crystalline structure.
The embedded silicon germanium for some electronic components will abut the shallow trench isolation, but the insulators typically used for shallow trench isolation do not support epitaxial growth. This results in a “ski slope” effect, where the embedded silicon germanium adjacent to the shallow trench isolation slopes into a channel or cavity that forms at the intersection of the shallow trench isolation and the embedded silicon germanium. Many transistors have a source and drain aligned to opposite sides of a gate, so the source/drain next to the shallow trench isolation is sloped and has a reduced volume compared to the other source/drain. This degrades the performance of the electrical component with embedded silicon germanium adjacent to a shallow trench isolation. As the commercial trend is for more circuitry on a chip, it may not be practical to move the embedded silicon germanium away from the shallow trench isolation.
Accordingly, it is desirable to provide integrated circuits with a shallow trench isolation that supports epitaxial growth of silicon germanium. In addition, it is desirable to provide methods for producing an integrated circuit with embedded silicon germanium adjacent to a shallow trench isolation that is comparable to embedded silicon germanium that is not adjacent to a shallow trench isolation. Furthermore, other desirable features and characteristics of the present embodiment will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.